Printing screen cleaner

ABSTRACT

Printing screens are carried through a tunnel by an overhead conveyor. In an enlarged central section of the tunnel are opposed rows of spray heads to direct a cleaning solvent at the screens under pressure. A solvent with material removed from the screens drains into a removable separating tray to extract at least a portion of the material from the solvent. The solvent then drains into a sump from which it is pumped back to the spray heads. At opposite ends of the central cleaning section are entrance and exit sections having doors which are pushed aside by the screen as it is moved through the tunnel. A fan draws air in from the ends of the tunnel and discharges it out a stack. Fire quenching means has spray heads in the tunnel.

United States Patent 2,549,070 4/1951 Drews.......

[72] Inventor JohnW. Key

606 Ironwood Drive, Arlington Heights, Ill. 2,766,764 10/ 1956 Bennett60004 3,049,135 8/1962 Kuhl et a1.

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P E -R b rtL.Bl t [54] PRINTING SCREEN CLEANER "Mary xammer o 6 cu geAttorneyDarbo, Robertson and Vandenburgh 11 Claims, 4 Drawing Figs.

ABSTRACT: Printing screens are carried through a tunnel by lnt. anoverhead conveyon In an enlarged central section of the [so] tunnel areopposed rows of spray heads to direct a cleaning Field of solvent at thescreens under pressure. A solvent with material removed from the screensdrains into a removable separating tray to extract at least a portion ofthe material from the solvent. The solvent then drains into a sump fromwhich it is [56] References Cited UNITED STATES PATENTS 971,745 10/1910Gungerich 2,154,559 4/1939 Bilde 2,399,205

pumped back to the spray heads. At opposite ends of the central cleaningsection are entrance and exit sections having 68/209 doors which arepushed aside by the screen as it is moved 134/97 through the tunnel, Afan draws air in from the ends of the 134/ I 48(UX) tunnel anddischarges it out a stack. Fire quenching means has 1/1947 Zademach eta1. 134/131X spray heads in the tunnel.

4/1946 Campbell........ 2,413,853

Patented May 25, 1971 2 Sheets-Sheet 1 Patented May 25, 1971 2Sheets-Sheet 2 PRINTING SCREEN CLEANER BACKGROUND OF THE INVENTION Inscreen printing an open mesh fabric has a design outlined therein byclosing the open mesh in some areas. The screen is then placed over thesurface to be printed and the printing dye, ink, paint, or the like(subsequently referred to as printing material) forced through theremaining open mesh areas onto the surface to be printed. Normally, itis worthwhile to salvage the screens after use. This is done by removingthe printing material with a suitable solvent, many of which are highlyflammable, while others may be caustic, etc., making them difficult orundesirable to handle. If the design of the screen is not to be reused,the screen is further cleaned to remove the material employed to definethe design. Usually the printing material is soluble in a differentsolvent from that which will remove the material employed to form thedesign, e.g., one may be soluble in lacquer thinner and the other inwater. The term solvent is employed herein to refer to a liquid whichwill wash out the material desired to be removed from the screen.

A number of different procedures have been employed from time to time toremove material from printing screens. Without attempting to enumeratethem all, these have included such practices as: dipping or immersing ina solvent; brushing the screen with a solvent; and placing the screen ina comparatively large enclosure in which there are moving, e.g.rotating, spray heads to direct a stream of solvent at the screen fromvarious angles. All of these have had one or more of variousdisadvantages. Any such cleaning process which requires individuals toparticipate in, or be near, the cleaning action are likely to involvehealth hazards. When cleaning with a highly flammable solvent there areserious dangers of fire and explosion. A dipping process requires anextremely large volume of solvent plus the fact that there is littlemechanical action to assist in the cleaning process. Moving spray headsrequire a comparatively large enclosure which obviously occupies spacethat might be otherwise used and which increases the size of thepotential explosion bomb. If there is not an enclosure about thespraying area there is a waste of costly solvents in overspray andobvious fire dangers.

The principal object of the present invention is to provide an apparatusfor cleaning printing screens or the like, and which overcomes thedisadvantages of the prior art devices and procedures. The apparatus isrelatively small and compact. There is little danger of fire and, shouldit occur, it can be readily controlled. The apparatus will accommodatevarious sizes of printing screens. It requires no manual labor exceptthat of loading the screen into the machine and unloading it. Theseoperations are performed in areas in which the health hazards, otherwisepresent, are avoided. Should the screen not be thoroughly cleaned in afirst pass through the machine. it is a simple matter to run the screenthrough the machine a second time. The solvent is continually reused andthere is extremely little loss from overspray. Before the solvent isreused, a substantial portion of the material removed from the screen isseparated from the solvent in a tray. This tray is removable so that theseparated material can easily be discarded.

Further objects and advantages will become apparent from the followingdescription taken in conjunction with the drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation, partially brokenaway, of an embodiment of the invention;

FIG. 2 is a section as viewed at line 22 of FIG. 1;

FIG. 3 is a section as viewed at line 3-3 of FIG. 2;

FIG. 4 is a partial section as viewed at line 44 of FIG. 2, with ashorter screen than that of FIGS. 1 and 3.

DESCRIPTION OF THE SPECIFIC EMBODIMENT The following disclosure isoffered for public dissemination in return for the grant ofa patent.Although it is detailed to ensure adequacy and aid understanding, thisis not intended to prejudice that purpose ofa patent which is to covereach new inventive concept therein no matter how others may laterdisguise it by variations in form or additions or further improvements.The claims at the end hereof are intended as the chief aid toward thispurpose; as it is these that meet-the requirement of pointing out theparts, improvements, or combinations in which the invention concepts arefound.

In the illustrated embodiment there is a frame, generally 10, whichforms an upper enclosure 11 and a lower enclosure 12. The lowerenclosure has a part of one wall in the form of a door 13 mounted onhinge 14. The upper enclosure 11 defines a tunnel l5 and is formed withan entrance section 16, an exit section 17 and a central cleaningsection 18.

The screen 21 to be cleaned is carried through the tunnel by a conveyor,generally 22. The conveyor comprises an endless roller chain 23 trainedfor movement about sprockets 24. Sprockets 24 are secured to shafts 25suitably journaled in frame 10. To one of shafts 25 is secured a pulley(not shown) which is engaged by belt 26 to rotate the shaft and move thechain. Belt 26 is driven by a pulley 27, driven at slow speed by motor28 through a speed reduction unit 29. Motor 28 is reversible so that thechain may be driven in either direction. Projection from one side ofchain 23 are a plurality of pins 32. Hangers 33 are releasably securedto the frames of screens 21 and have, at their upper ends, openings toreceive pins 32 so that the hangers may be releasably connected to chain23.

A plurality of doors, generally 34, are provided in the en trance andexit sections of the tunnel. The structure of these doors is best seenin FIG. 4. They comprise a mounting member or holder 35 secured to theappropriate wall of the section. To each of the holders is secured oneof the ends of a plurality of individual gates 36. The opposite end ofthe gates projects substantially to the opposite wall of the tunnel. Thegates are biased so as to have a normal position transverse to thetunnel, but they are movable so that they may be individually pushedaside by the screen 21 as it moves through the tunnel. While such gatesmay be formed in diverse ways, I prefer to form them of a continuouslength of rubber or flexible plastic, one edge of which is held byholder 35. The portion of the strip projecting from the holder is slitat regular intervals to define the individual gates 36. For clarity ofillustration the size of the slits is emphasized in FIG. 4. As best seenin FIG. 2, in the entrance section 16 the holder 35 of one door isaffixed to one wall, while the holder 35 of the adjacent door is affixedto the other wall. The same arrangement is used in exit section 17.

To ensure that screen 2] remains centered in the tunnel during itsmovement therethrough, there are pairs of guide wires or thin rods 37 atopposite sides of the path of travel of the screen. These wires are heldby mounting brackets 38 at the entrance and exit ends of the tunnel.

The bottom of the upper enclosure 11 has a drain opening 42therethrough. One end of a tray 43 is below this opening. As best seenin FIG. 1, tray 43 is mounted in guides 44 so that it is removable.Adjacent the other end of the tray is a drain opening 45. Between theends of the tray are a plurality of dividers or dams which separate thetray into a series of settling basins. While the dividers 46 can besolid, I prefer to have them solvent-permeable so that some filteringeffect takes place as well as having the solvent overflow the tops ofthe dividers. The dividers are of different heights so as to formsettling basins of different depths.

Below opening 45 in the tray is an opening 37 in the top of a container48 forming a solvent sump. A trap connection 49 permits any overflow ofthe sump to be discharged into a sewer or the like. In normal operationthis is not used but it may be necessary to handle excess liquid whichmay be discharged into the sump should the fire protection equipment beactuated as hereinafter described. Container 48 is provided withremovable connections so that it may be taken out for cleaning shouldthat be necessary.

The intake line 52 of a, motor drivenpump 53 communicates with sumpcontainer 48. The discharge line 54 of the pump communicates with a pairof headers 55 positioned on opposite sides of the central section 18 ofthe tunnel. On headers 55 are a plurality of spray heads 56, each ofwhich directs the solvent 57 under pressure at various directionstowards the opposite sides of the screen, as illustrated. A window 58 isprovided in one wall of the central enclosure 18 through which thecleaning action may be observed.

The upper enclosure 11 includes a stack 61 through which air and vaporsmay be discharged elsewhere. In the stack is a fan 62, belt driven by amotor 63. The fan forces the air and vapors out through the stack and atthe same time draws fresh air in past the doors at the two ends of thetunnel. This negative air pressure in the tunnel prevents any of thevapors escaping into the area immediately adjacent the cleaningapparatus and thus reduces the danger of fire and explosion. Twoautomatic sprinkler heads 64 are positioned in the interior of theenclosure at the opposite ends of the central section 18. A thirdautomatic sprinkler head 65 is positioned in stack 61. Pipes 66 connectthe sprinkler heads to a suitable source (not shown) of fireextinguishing fluid, such as water or carbon dioxide. As isconventional, the sprinkle heads will automatically open in the eventoffire in the enclosure.

The screen 21 to be cleaned first has the hangers 33 attached thereto,if they are not permanently affixed. The hangers 33 are then hung onpins 32 on the lower run of chain 23 at one (or the other) end of thetunnel. Sprockets 24 are positioned sufficiently far from the ends ofthe tunnel to permit the hanging of the screen on the chain before thescreen must enter the tunnel.

Motor 28 is then energized to move the screen slowly through the tunnel.A speed of movement, for example, of 6 inches per minute is eminentlysatisfactory. The pump 53 is, of course, energized to force the cleaningfluid 57 out of spray heads 56. As the screen slowly moves past thespray heads, the angle of incidence of the solvent onto the screen isconstantly changing with respect to any one portion of the screenbecause of the spread of the spray produced by the spray heads. Thisplus the force of the fluid and the solvent action does an excellent jobof cleaning the screen.

As the screen leaves the cleaning section 18 and enters the exit section17, the fluid drains from the screen so that by the time the screen iscompletely out of the tunnel it is dry for all practical purposes. Thedoors 34 only open to the extent necessary to permit the passage of thescreen. This, plus the use of multiple doors, prevents the loss of thesolvent out through the exit or entrance portions of the tunnel. If itshould turn out that the material on the screen has gotten particularlyhard and requires extra cleaning, it is only necessary to reverse motor28 and cause the screen to move through the tunnel in the reversedirection, thus obtaining a second cleaning. Substantial amounts of thematerial removed from the screen will settle in the tray 43, the amountdepending upon the specific material, the solvent, etc. After a day'suse, or more frequently if necessary, and while the pump 53 is shutdown, the door 13 is opened and tray 43 removed. The material trappedtherein can be removed and disposed of. The tray 43 then is returned toits proper position as illustrated.

lclaim:

1. An apparatus for cleaning objects of approximately a givenwidth,'such as printing screens, with a liquid solvent to removematerial from the object, said apparatus comprising:

a frame;

enclosure means on said frame and defining a tunnel through which theobject can pass, said tunnel having a central cleaning section andentrance and exit sections at opposite sides of the central section, anddefining an exhaust duct communicating with said central section, saidenclosure means having a bottom with an opening therein through whichliquid solvent can drain, said sections all being closed at the top,said entrance and exit sections having doorways at the distal endsthereof through which said object can enter and leave the enclosuremeans, there being a linear path between said doorways and through saidsections, said entrance and exit sections being narrower in a directiontransverse to said path than is said central section and only slightlywider than said given width;

conveyor means mounted on said frame and trained for movement along saidpath extending from beyond said doorways and through said tunnel forsupporting and moving one of said objects through said tunnel;

cleaning means mounted on said frame and including,

a sump below said bottom and positioned to receive solvent from saidopening,

spray means in said central section and at opposite sides of the path ofthe object to direct sprays of liquid solvent under pressure at oppositesides of the object, and

pump means communicating with said sump and said spray means to withdrawsolvent from said sump and to deliver it under pressure to said spraymeans;

fan means in said enclosure for producing a flow of air into thedoorways of the entrance and exit sections and out through said exhaustduct; and

fire quenching means in said enclosure including a spray head todischarge a fire quenching substance upon the occurrence of a fire.

2. An apparatus as set forth in claim 1, wherein said cleaning meansincludes separating means to remove material from said liquid solvent.

3, An apparatus as set forth in claim 2, wherein said separating meanscomprises a removable tray between said opening and the sump to receiveliquid and material from the opening adjacent one end of the tray and todischarge into the sump from a point adjacent the other end of the tray,said tray having a series of dividers thereacross between said ends ofthe tray to divide the tray into a series of basins.

4. An apparatus as set forth in claim 3, including door means in saidentrance and exit sections, said door means being normally closed andbeing pushed open by the object as it moves through the through thetunnel, each door means comprising a plurality of gates arranged in anapproximately vertical row, said gates being affixed to one side of theenclosure means and extending to'adjacent the other side of theenclosure means, said gates being individually biased to a positiontransverse to the path and being individually movable to a positionalong said one side of the enclosure means.

5. An apparatus as set forth in claim 4, wherein in each of saidentrance and exit sections there is one vertical row of said gatesaffixed to a first side of the enclosure means and a second vertical rowof said gates affixed to a second side of the enclosure means, saidfirst and second rows being spaced from each other along said path.

6. An apparatus as set forth in claim 1, wherein said apparatus includesdoor means in said entrance and exit sections, said door means beingnormally closed and being pushed open by the object as it moves throughthe tunnel and in each of said entrance and exit sections there is onevertical row of door means affixed to a first side of the enclosuremeans and a second vertical row of door means affixed to a second sideof the enclosure means, said first and second rows being spaced fromeach other along said path.

7. An apparatus as set forth in claim 6, wherein each door meanscomprises a plurality of gates arranged in an approximately verticalrow, said gates being affixed to one side of the enclosure means andextending to adjacent the other side of the enclosure means, said gatesbeing individually biased to a position transverse to the path and beingindividually movable to a position along said one side of an enclosuremeans.

8. An apparatus for cleaning objects of approximately a given width,such as printing screens, with a liquid solvent to remove material fromthe object, said apparatus comprising:

a frame;

enclosure means on said frame and defining a tunnel through which theobject can pass, said tunnel having a central cleaning section andentrance and exit sections at opposite sides of the central section,said enclosure means having an opening in the bottom thereof throughwhich liquid solvent can drain, the tunnel at said entrance and exitsections being only slightly wider than the width of the object and thetunnel at the cleaning section being substantially wider than at theentrance and exit sections;

door means in both the entrance and exit sections for normally closingthe tunnel at said entrance and exit sections and being pushed open bythe object as it moves through the tunnel, each door means comprising aplurality of gates arranged in an approximately vertical row, said gatesbeing affixed to one side of the enclosure means and extending towardthe other side of the enclosure means, said gates being individuallybiased to a position transverse to the path and being individuallymovable to a position along said one side of the enclosure means;

conveyor means mounted on said frame and trained for movement along apath through said tunnel for supporting and moving one of said objectsthrough said tunnel; and

cleaning means mounted on said frame and including,

a sump below said enclosure and positioned to receive solvent from saiddrain,

spray means in said central section and at opposite sides of the path ofthe object to direct sprays of liquid solvent under pressure at oppositesides of the object, and

pump mean communicating with said sump and said spray means to withdrawsolvent from said sump and to deliver it under pressure to said spraymeans.

9. An apparatus as set forth in claim 8, wherein said cleaning meansincludes separating means to remove material from said liquid solvent.

10. An apparatus as set forth in claim 9, wherein said separating meanscomprises a removable tray between said opening and the sump to receiveliquid and material from the opening and the sump to receive liquid andmaterial from the opening adjacent one end of the tray and to dischargeinto the sump from a point adjacent the other end of the tray, said trayhaving a series of dividers thereacross between said ends of the tray todivide the tray into a series of basins.

11. An apparatus as set forth in claim 8, wherein in each of saidentrance and exit sections there is one vertical row of said gatesaffixed to a first side of the enclosure means and a second verticalrowof said gates affixed to a second side of the enclosure means, saidfirst and second rows being spaced from each other along said path.

1. An apparatus for cleaning objects of approximately a given width,such as printing screens, with a liquid solvent to remove material fromthe object, said apparatus comprising: a frame; enclosure means on saidframe and defining a tunnel through which the object can pass, saidtunnel having a central cleaning section and entrance and exit sectionsat opposite sides of the central section, and defining an exhaust ductcommunicating with said central section, said enclosure means having abottom with an opening therein through which liquid solvent can drain,said sections all being closed at the top, said entrance and exitsections having doorways at the distal ends thereof through which saidobject can enter and leave the enclosure means, there being a linearpath between said doorways and through said sections, said entrance andexit sections being narrower in a direction transverse to said path thanis said central section and only slightly wider than said given width;conveyor means mounted on said frame and trained for movement along saidpath extending from beyond said doorways and through said tunnel forsupporting and moving one of said objects through said tunnel; cleaningmeans mounted on said frame and including, a sump below said bottom andpositioned to receive solvent from said opening, spray means in saidcentral section and at opposite sides of the path of the object todirect sprays of liquid solvent under pressure at opposite sides of theobject, and pump means communicating with said sump and said spray meansto withdraw solvent from said sump and to deliver it under pressure tosaid spray means; fan means in said enclosure for producing a flow ofair into the doorways of the entrance and exit sections and out throughsaid exhaust duct; and fire quenching means in said enclosure includinga spray head to discharge a fire quenching substance upon the occurrenceof a fire.
 2. An apparatus as set forth in claim 1, wherein saidcleaning means includes separating means to remove material from saidliquid solvent.
 3. An apparatus as set forth in claim 2, wherein saidseparating means comprises a removable tray between said opening and thesump to receive liquid and material from the opening adjacent one end ofthe tray and to discharge into the sump from a point adjacent the otherend of the tray, said tray having a series of dividers thereacrossbetween said ends of the tray to divide the tray into a series ofbasins.
 4. An apparatus as set forth in claim 3, including door means insaid entrance and exit sectioNs, said door means being normally closedand being pushed open by the object as it moves through the through thetunnel, each door means comprising a plurality of gates arranged in anapproximately vertical row, said gates being affixed to one side of theenclosure means and extending to adjacent the other side of theenclosure means, said gates being individually biased to a positiontransverse to the path and being individually movable to a positionalong said one side of the enclosure means.
 5. An apparatus as set forthin claim 4, wherein in each of said entrance and exit sections there isone vertical row of said gates affixed to a first side of the enclosuremeans and a second vertical row of said gates affixed to a second sideof the enclosure means, said first and second rows being spaced fromeach other along said path.
 6. An apparatus as set forth in claim 1,wherein said apparatus includes door means in said entrance and exitsections, said door means being normally closed and being pushed open bythe object as it moves through the tunnel and in each of said entranceand exit sections there is one vertical row of door means affixed to afirst side of the enclosure means and a second vertical row of doormeans affixed to a second side of the enclosure means, said first andsecond rows being spaced from each other along said path.
 7. Anapparatus as set forth in claim 6, wherein each door means comprises aplurality of gates arranged in an approximately vertical row, said gatesbeing affixed to one side of the enclosure means and extending toadjacent the other side of the enclosure means, said gates beingindividually biased to a position transverse to the path and beingindividually movable to a position along said one side of an enclosuremeans.
 8. An apparatus for cleaning objects of approximately a givenwidth, such as printing screens, with a liquid solvent to removematerial from the object, said apparatus comprising: a frame; enclosuremeans on said frame and defining a tunnel through which the object canpass, said tunnel having a central cleaning section and entrance andexit sections at opposite sides of the central section, said enclosuremeans having an opening in the bottom thereof through which liquidsolvent can drain, the tunnel at said entrance and exit sections beingonly slightly wider than the width of the object and the tunnel at thecleaning section being substantially wider than at the entrance and exitsections; door means in both the entrance and exit sections for normallyclosing the tunnel at said entrance and exit sections and being pushedopen by the object as it moves through the tunnel, each door meanscomprising a plurality of gates arranged in an approximately verticalrow, said gates being affixed to one side of the enclosure means andextending toward the other side of the enclosure means, said gates beingindividually biased to a position transverse to the path and beingindividually movable to a position along said one side of the enclosuremeans; conveyor means mounted on said frame and trained for movementalong a path through said tunnel for supporting and moving one of saidobjects through said tunnel; and cleaning means mounted on said frameand including, a sump below said enclosure and positioned to receivesolvent from said drain, spray means in said central section and atopposite sides of the path of the object to direct sprays of liquidsolvent under pressure at opposite sides of the object, and pump meancommunicating with said sump and said spray means to withdraw solventfrom said sump and to deliver it under pressure to said spray means. 9.An apparatus as set forth in claim 8, wherein said cleaning meansincludes separating means to remove material from said liquid solvent.10. An apparatus as set forth in claim 9, wherein said separating meanscomprises a removable tray between said opening and the sump to receiveliquid and material from the openIng and the sump to receive liquid andmaterial from the opening adjacent one end of the tray and to dischargeinto the sump from a point adjacent the other end of the tray, said trayhaving a series of dividers thereacross between said ends of the tray todivide the tray into a series of basins.
 11. An apparatus as set forthin claim 8, wherein in each of said entrance and exit sections there isone vertical row of said gates affixed to a first side of the enclosuremeans and a second vertical row of said gates affixed to a second sideof the enclosure means, said first and second rows being spaced fromeach other along said path.